This invention relates to an apparatus and a method for producing an as-cast product by using horizontally split type metal molds and a holding furnace as in low pressure casting, vacuum casting, or different pressure casting.
Casting machines using a holding furnace are well known, as, for example, in JP, A, 63-273561. A conventional casting machine described in that Japanese patent is shown in FIG. 9. The casting machine 101 includes four supporting columns 102, which constitute an outer frame, with each column of the frame being fixedly mounted on a base 103. A truck 104, which carries a holding furnace 105, runs along the base 103. The machine has a cylinder 107 mounted on the top of the supporting columns 102 for supporting a metal cope 106 from above.
The casting machine has some problems. The first is that since the cylinder 107 is mounted on the tops of the columns 102, the casting machine has a high profile. Thus a normal-size lorry cannot carry the entire casting machine when it is at its full height. Accordingly, when transferred by such a lorry, the casting machine has had to be divided, or disassembled, into two pieces, i.e., an upper portion and a lower portion, or three pieces. Assembling these pieces requires much labor and time.
The second is that since the machine uses an upwardly-facing cylinder on the tops of the columns 102, the machine must use many parts. Inherently it does not have enough force to demold an as-cast product that requires a large demolding force.
The third is that since the machine uses a single cylinder for lifting the metal cope, the cope cannot be held horizontally when lifted. Further, the cope cannot be adjusted, or compensated for, to be in a horizontal position when it is not held horizontally during the vertical movement. Accordingly, due to an inadequate mating (or closing) of molds, the molten metal, which is now poured into the molds, may escape from the molds at the joint between them and may cover a part of the molds. Thus, an undesired shape of a product may be produced, and the escaped metal, which covers the molds, may make it difficult to demold the product, thereby stopping the operation of the cylinder or producing scratches on the surface of the product.
The present invention has been conceived in view of the problems described above. The purpose of the invention is to provide a low-profile casting machine that uses horizontally split type metal molds and a holding furnace, wherein the metal cope is held horizontally when moved vertically and when mated with a horizontally held metal drag.
Another purpose of the invention is to provide a method to operate the casting machine of the invention.
In one aspect of the casting machine of the invention for producing an as-cast product by using horizontally split type metal molds to be closed to define a cavity and by pouring molten metal from a holding furnace into the cavity, the machine includes a metal drag fixedly and horizontally located; a plurality of upwardly-facing cylinders mounted on a floor or a base around the metal drag, each cylinder having a cylinder rod that extends and retracts; and a cope die base mounted for vertical movement on the distal ends of the upwardly-facing cylinders for horizontally holding a metal cope at a position above the metal drag so that the metal cope is mated with the metal drag to define the cavity when the cope die base is lowered by the cylinders.
The casting machine may be provided with means for detecting whether the metal cope is held horizontally by measuring the displacement of the metal cope, at some horizontally different positions, from a predetermined position or from set patterns for mold closing and mold opening. The casting machine may also be provided with means for adjusting the extension or retraction of the cylinder rods of the upwardly-facing cylinders to horizontally hold the metal cope when it is not held horizontally.
In one example of the above aspect, the cope die base may be connected to distal ends of the cylinder rods through releasable clampers, each of which has a low profile. Releasing these dampers is easily performed, and it allows the cope die base to expand or contact freely when it is subjected to heat stresses while being supported by the upwardly-facing cylinders. This releasing also allows the cope die base to be separated easily from the upwardly-facing cylinder, if desired, for transporting it.
In the present invention a xe2x80x9ccasting machinexe2x80x9d generally means a machine for producing an as-cast product by using a holding furnace from which molten metal is poured into the cavity defined by metal molds, as in low pressure casting, vacuum casting, or different pressure casting. Further, set patterns for mold closing and mold opening mean a schedule for the intended displacement of a cope from a predetermined position over time.
If the casting machine of the present invention is provided with lifting cylinders located under the holding surface for vertically moving it, the machine will have an advantage in that it will be more compact than a conventional casting machine that uses a jack located at a lower frame to lift the holding furnace toward the metal molds.
Further, in the present invention the cylinders may be oil hydraulic, pneumatic, or electric (servomotor-driven) cylinders. If the cylinders are electric cylinders, the structure of the casting machine will have an advantage in that it will be simple, because oil hydraulic and pneumatic cylinders require some pipes and pressure pumps for the working fluid.
According to the casting machine of the present invention, it does not require such an upper frame structure that is required in the conventional machine discussed above. Thus the casting machine of the present invention can be of a low profile and of less weight.
Other purposes, aspects, examples, and advantages of the present invention will be apparent by the following description made by reference to the accompanying drawings.